Variable-throw crank for bicycles



- .1. E. POYSER 1.714.134

VARIABLE .THROW CRANK FOR BICYCIJES May 21, 1929.

2 Sheets-Shoot 1 Filed Jan. 51, 1928 IN VEN TOR.

JamqWn ay 1929- r J. E. POYSER' VARIABLE} THROW CRANK FOR BICYCLES Filed Jan. 31, 1928 2 Sheets-Sheet 2 IN VEN TOR. fimexfifigyse r':

Patented May 21, 1929.

- NI ED- STA Janus E. roYsER, or SAN naanorsco, camroama.

VARIABLE-THROW CRANK FOR BIGYCLES.

Application filed January 31, 1928. Serial No. 250,940.

This invention relates to a variable throw crank for bicycles, and its special object is to produce a crank which will enable the user to have a greater leverage on the bicycle on the down throw than on by making it more convenient to operate, and giving the feet less travel on the up throw than on the down throw, whereby the operation of driving the bicycle is more easily effected.

Another object of the invention is to provide means whereby the friction on the apparatus for shifting the pedal from the minimum throw to the maximum throw and vice versa will be reatly reduced.

A further 0 ject ofthe invention is to provide a dustguard for the crankoperating apparatus which will prevent the ball bearings used at the end of the crank from getting filled with dust.

Other objects of the invention will parent as the descri tion proceeds;

An embodiment o the'invention is shown in the accompanying drawings in which the be apsame portion throughout the several figures of thedrawings and of which there may be modifications.

F'gure 1 is a side elevationof a bicycle sprocket wheel, one crank, and a portion of the apparatus for shifting the pedal from one position to the other, certain. of the parts being removed for purpose of illustration, Figure 2 is a pllan view of the crank shown in Figure 1, wit the cover removed,

. Figure 3 is a side elevation on a slightly larger scale of the endof the crank, the guide disk and its hand groove being shown,

Figure 4 is a sectional view through the crank showingthe bearings for guiding the pedal and pedal pin,

Figure 5 is an edge view of the dust guard, and

Figure 6 is a side elevation of the disk to which the pedal pin 'is secured.

The sprocket wheel is' indicatedat- 1, the

main bearing pin therefor at 2, the crank 3 is secured to the main bearing pin 2 and has 5 v aslot thereiniat its end as indicated at 4.

Adjacent the inner end of the slot of the crank there is a pin 5 which has some balls 6 bearing thereon, which balls run a groove the up throw, thereflat nut 15, this same reference numeral is applied to the 7 in the disk 8, said disk having the pedal pin 9 projecting therefrom, either as a unit as shown or as an independent pin.

The pin 9 has raceways for two sets of'balls 10 and 11 which balls carry the rings 12 and 13 to'bear upon the slot the pedal pin travels. 14 which is assembled and secured in here is another disk on the pedal pin 9 place thereon by means of a disk has the rivets16 and 17 for securing the pedal frame 18 thereto, said frame carrying the toe clip 19 to prevent the frame from being turned upside down.

is a guard ring20, said guard ring being flanged inwardly at 21 to prevent it from being displaced from its proper position.

It will be noted that as the crank-turns in the crank in which I On the outside of the disks 8 and14 there around that the pedal frame '18 remainsin g the same horizontal position, and this will cause the pedal frame and pin to travel to-- ward and from the end of the crank, and as the pressure of the foot on-the vpin causes a slight twisting of the pedal pin with respect to the crank, the rings 12 and 13 will rotate reversely, that is, one Willbear harder on the lower portion of the slot'while at the same time the other is bearing harder on the upper portion of the slot.

The'groove 7 is wider at 7 to allow'the pedal to rise without bringing it back'to the short radius too soon on-the down stroke. In the event that the rider of the bicycle goes down a steep hill, he may turn thepedal over if he'desires in which event the condiv 7 time with respect tolthe crank will be reversed and he thereby is able to brake the machine with more advanta e.

V Having thus described my invention, what I, desire to secure by LettersPatent of the United States is as follows, but modifications may be made in carrying out the invention as shown in the drawing and in the above particularly described form thereof, within;

the purview of the annexedclaims:

1. A crank for bicycles comprising an arm,

a revoluble shaft adapted to carrythe same;

said arm having a slot therein, a pedal frame,

a pedal pin for supporting said frame. in V A 7 'said slot, ball bearings in said slot, a: diskv to which said pin is connected, an annular groove in said disk, apin von said arm extended into said groove to cause the travel of the pedal pin with respect to the crank from groove in said disk, a pin fixed in said crank one end of the slot to the other as said crank arm and extending into said groove, 2. 10 revolves. second disk on said pedal pin, and a pedal 2. A variable throw crank for bicycles frame on said pedal pin attached to said comprising a crank arm having a longitu- Second disk. dinal slot in the end thereof, a pedal pin in In testimony whereof I have hereunto set said slot, a pair of ball bearings on said pin my hand this26 day of January, A. D. 1928.

in said slot, a disk'on said pin, an annular JAMES E. POYSER. 

